Ultrasound waves with a twist

An international team of physicists has simultaneously measured the angular momentum and torque exerted by acoustic waves for the first time. It found that this ratio agrees exactly with the predicted theory for acoustic and optical waves. According to the researchers, their techniques may also have potential in medical imaging and treatment.

A fundamental principle of optics and acoustics is that waves carry momentum, and can therefore exert a force. Equally important is the notion that they can also carry angular momentum and exert a torque. The ratio between these two quantities – the push and the twist – is central to the physics of waves and has long been taken for granted without direct experimental proof of its validity.

Difficulties with optics

The concept of radiation pressure has traditionally been explored and exploited in optics – for example, it is the basis of the "optical tweezers" used to grab and manipulate microscopic objects in microbiology and nanotechnology. The force of a light beam is equal to its power divided by the speed of light. Its torque is proportional to the radiation pressure, which depends on the varying properties of acoustic and optical beams. Because the speed of light is extremely large, the force and torque exerted by a light beam are very small and therefore difficult to measure. To complicate matters further, it is hard for scientists to work out precisely how well an object absorbs linear and angular momentum from a light beam, and hence to calculate the forces and torques exerted.

Sound versus light

For these reasons, nobody has ever managed to measure simultaneously the force and torque of a light beam on an object. Fortunately, the same equations apply in acoustics, where the speed of light is replaced by the much smaller speed of sound. A sound beam of the same power therefore exerts both a stronger push and twist, making it easier to measure the ratio between the two.

Now, ultrasound physicist Christine Demore, biophotonics researcher Mike MacDonald and colleagues from the Institute for Medical Science and Technology at the University of Dundee in the UK, together with Gabriel Spalding from Illinois Wesleyan University in the US, have levitated and twisted a rubber puck in water by bombarding it with a "vortex beam" of ultrasound – a twisted coil of sound shaped a bit like a DNA double helix. This was done to verify experimentally the angular momentum to torque ratio and directly prove this fundamental theory. The researchers found – as expected – that the ratio of the torque to the linear force on the puck was equal to the ratio of the number of intertwined helices per wavelength.

Applications beyond physics

"The key part of the paper is the fact that we've demonstrated that ratio," explains MacDonald, "but the advance that we had to make to get that result was the level of control over the ultrasound beams, which hasn't been possible before." Demore adds that developing focused ultrasound has applications well beyond pure research. "There's a whole field developing of using ultrasound to kill tumours completely non-invasively," she says. There is also a project to develop "sonotweezers" that are based on optical tweezers but which are able to move larger and heavier objects.

Optical physicist Miles Padgett from the Glasgow University in the UK describes the work as "a beautiful experiment". He feels that "people active in the field won't be surprised by the ratio because essentially the results show are as one would expect". "But if you never checked the things that we know, you'd never find the things that we don't," he says.

The paper has been accepted for publication in Physical Review Letters.

About the author

Tim Wogan is a science writer based in the UK

30 comments

Next stage for light?

Good work to show that the ratio of the torque(due to angular momentum of the vortex beam) to the linear force( from linear mommentum of the beam) = ratio of the intertwined helices/ wavelength, as foreseen by the theory. This should encourage somebody in the field to go at the much weaker ratio for light mainly due to the much higher speed of light than that of sound.

Angular momentum of EM field

Indeed, due to angular symmetry, Noether theorem guards angular momentum conservations for both fields. To create twist-like wave for EM field, we would have to twist something extremely fast ... but isn't it already done by the nature? Atom deexcitation changes spin of electron by 1: e.g. from -1/2 to +1/2 ... it is just rotation by 180deg in times of scales of attoseconds - angular momentum conservation says that there should be created twist-like wave:optical photon carrying angular momentum (picture).

So can we directly observe angular momentum of photons? Would beam of circularly polarized light make something rotate?I doubt it - rotation of 180deg is first angular acceleration then deceleration - carried difference of angular momentum is zero - it only rotates (change orientation of/is absorbed by) single electrons.

Forward & angular momentum in ether nodes

It is wonderful that the Dundee team has experimentally verified the theoretical predictions. The question remains is: exactly how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum? I have described a simple and straightforward qualitative answer: Dielectric ether nodes interact by rotating in place and inducing their momentum to neighbouring nodes creating a wave pattern (not point-like photons) in the universal lattice of such nodes. The angle formed by the axis of a node's rotation and a line between it and the next node determines whether the momentum transmitted is angular or forward. A 90 degree angle induces forward momentum. A zero angle induces angular momentum in the wave. At other spherical angles both types of momentum will be induced creating the spinning wave phenomena. See Figs. 5 and 8 of my 2005 Beautiful Universe paper . I distinguish between the node rotation and the spin of the wave as a whole made up of the pattern of individually rotating nodes

Vladimir, I've tried to emphasize that I'm talking about optical photons. I completely agree that they are not exactly point-like. I cannot find the reference now, but there is simple and convincing experiment to measure the "length in space of single photon": add a delay in one arm of Mach-Zehnder interferometer - larger than about pi/2 destroys the interference of single photons.Twist-like wave in water quickly dissipates, but EM field has no viscosity and so optical photon can travel practically undeformed for millions of years - is very stable dynamical configuration of EM field (soliton).

Thanks for the reference to Eric Stanley Reiter experiments that there is a signal on both paths for splitted single gamma ray - is there any independent confirmation?Gamma rays are created in muuuch more complex: nuclear processes and carry much larger energy, so I wouldn't be surprised if they behave in a more complicated way.If Reiter's effect is true, one explanation might be the "theta/pilot wave" conjugated with particle (like in great Couder's experiments) - for gamma rays it should have much larger energy, which might be directly observed.Another explanation might be e.g. that their more complicated EM configuration is similar to of two or more "photons" - can we measure independently their wavelength (not only energy carried)? Ok, the width of the signal, but it carries many artifacts...?Generally the interaction of gamma ray with beamplitter might be not so neutral like for optical photons...

Vladimir, another reason that hypothetical division of gamma ray wouldn’t worry me, is that quantization of some waves doesn’t imply that all of them are quantized. Just oppositely – it’s continuous wave what is natural for all fields, while discretization is something special. For water, because of nonlinearity there can be a tsunami – localized wave – soliton. But much more natural is angular symmetric wave when you throw a rock into water – not quantized. And so for EM field there are symmetric antennas, like single electron circulating in a perfect circle – produced EM field should be symmetric, not occur to be consisted of discrete particles. Another example is Cosmic Microwave Background – just thermal noise of EM thermodynamical degrees of freedom - imagining it as being consisted of discrete photons sounds very wrong. Discrete photons are freely used in perturbative picture, but we need to have in mind that it is only approximation (often divergent…) – the underlying field is continuous. To make it localized in discrete portions there are required some special mechanisms, like topological constrains (e.g. winding number) or availability of twist-like wave in non-viscous EM field: optical photons.

John, we should be more careful while drawing such pretty knots and Lord Kelvin didn’t rather have basis for that. For example in field theory such 1D entities can easily reconnect, disentangling such hypothetical knot – there would be required some special mechanisms to prevent that.Rayne, imagine a wave behind marine propeller ...

Photon orbital angular momentum

Jarek, a photon is bosonn with a an intrinsic spin value = 1 (in hbar unit; h Planck constant). One can twist it with an appropriately constructed transmission antenna to give it any appropriate orbital angular momentum expressed as L=1.2.3, ... (in hbar unit). This was recently done experimentally in Venice, where the team involved with the experiment, twisted it with L=1 and were able to transmit two different EM channels at the same frequency of the transmission band. This was discussed thoroughly in the Physicsword somewhere in the last two months.May be the PW team can fish out the reference and display it nere.

Indeed, due to angular symmetry, Noether theorem guards angular momentum conservations for both fields. To create twist-like wave for EM field, we would have to twist something extremely fast ... but isn't it already done by the nature? Atom deexcitation changes spin of electron by 1: e.g. from -1/2 to +1/2 ... it is just rotation by 180deg in times of scales of attoseconds - angular momentum conservation says that there should be created twist-like wave:optical photon carrying angular momentum (picture).

So can we directly observe angular momentum of photons? Would beam of circularly polarized light make something rotate?I doubt it - rotation of 180deg is first angular acceleration then deceleration - carried difference of angular momentum is zero - it only rotates (change orientation of/is absorbed by) single electrons.

Thanks Ashgar – I will look at it. But if there would be a rock enforced to circulate underwater, besides some symmetric wave around, it would also create a vortex: a twist-like wave carrying angular momentum in the central axis.What is strange about electron here is the quantization of angular momentum – it is a result of the wave nature of electron (rock doesn’t have ... but Couder's droplets have) – that particles are conjugated with waves they constantly create. So for example to find a resonance with the field, while making single orbit, the wave nature (internal clock) has to make integer number of “ticks” (Bohr-Sommerfeld condition). Great intuition about such resonance with the field provides Couder’s experiments – see video and papers I’ve linked above.

Linear momentum and angular momentum

Vladimir, there is no mystery as was discussed thread bare during the recent "interference conclave" in the PW, that each partcle is wavy and each wave is particle-like in nature via the de Broglie relation. A moving wave, through its "particleness", must have linear momentum and this was used to understand and explain the photo-electric effect by some Einstein. Moreover, as for the sound waves, one can also construct an appropriate antenna (twister) for the EM waves (photons) to twist them with a given orbital angular momentum L. This was demonstrated recently in Venice (see in PW somewhere during the last two months) by a team who twisted the EM wave (photon) through L=1 and managed to transmit two distinct EM channels at the same frequency of the frequency band. As a conclusion: In QM, a photon as a boson has an intrinsic spin value = 1h bar and has a forward momentum =E/c = hν/c, where E is its energy, but it can also be twisted like the sound waves here to have the different values of orbital angular momentum L. One can perhaps show the same thing is some more picturesque and earthly way, but the things as they are, they are quite clear.

It is wonderful that the Dundee team has experimentally verified the theoretical predictions. The question remains is: exactly how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum? I have described a simple and straightforward qualitative answer: Dielectric ether nodes interact by rotating in place and inducing their momentum to neighbouring nodes creating a wave pattern (not point-like photons) in the universal lattice of such nodes. The angle formed by the axis of a node's rotation and a line between it and the next node determines whether the momentum transmitted is angular or forward. A 90 degree angle induces forward momentum. A zero angle induces angular momentum in the wave. At other spherical angles both types of momentum will be induced creating the spinning wave phenomena. See Figs. 5 and 8 of my 2005 Beautiful Universe paper . I distinguish between the node rotation and the spin of the wave as a whole made up of the pattern of individually rotating nodes

just a trivial thing

Thanks Ashgar – I will look at it. But if there would be a rock enforced to circulate underwater, besides some symmetric wave around, it would also create a vortex: a twist-like wave carrying angular momentum in the central axis.What is strange about electron here is the quantization of angular momentum – it is a result of the wave nature of electron (rock doesn’t have ... but Couder's droplets have) – that particles are conjugated with waves they constantly create. So for example to find a resonance with the field, while making single orbit, the wave nature (internal clock) has to make integer number of “ticks” (Bohr-Sommerfeld condition). Great intuition about such resonance with the field provides Couder’s experiments – see video and papers I’ve linked above.

Asghar, I think you meant this article: physicsworld.com…a-new-twist-on-radioIndeed extremely interesting. I thought about (micro-)orbit quantization of electrons, but as I understood, it is instead quantization of quantum phase (water don't have) because of the proper choice of velocity of circulating electrons. Created optical vortex is something very different from optical photons - like behind marine propeller - I think it could literally make something macroscopic rotate(?).'However, I think the belief in infinite informational capacity is greatly overestimated - like nonzero noise reduce capacity of continuous function to finite one by Shannon-Harley theorem. Using angular momentum would only add some degrees of freedom to it.ps. I apology for misspelling your name.

Update: Ragtime, thanks for the video - ok, I have to think about it. The rotation was not made by absorption, but some complex indirect interaction - could we rotate macroscopic object by just absorbing optical photons?

de Broglie relation

Jarek, the de Broglie relation linking the wavelength of a particle of mass, through the Planck constant h, which itself is an element of phasespace, to its linear momentum mv : λ = h/mv, is precisely based on the Bohr-Sommerfeid resonance condtion. This relation we work with everyday. Yes, this relation through its haïkic simplicity and sharpness is worth meditating, because it was and is the corner stone for all the apparatus of QM. If you can digest this, you would have tasted something of the divinity of nature!

Thanks Ashgar – I will look at it. But if there would be a rock enforced to circulate underwater, besides some symmetric wave around, it would also create a vortex: a twist-like wave carrying angular momentum in the central axis.What is strange about electron here is the quantization of angular momentum – it is a result of the wave nature of electron (rock doesn’t have ... but Couder's droplets have) – that particles are conjugated with waves they constantly create. So for example to find a resonance with the field, while making single orbit, the wave nature (internal clock) has to make integer number of “ticks” (Bohr-Sommerfeld condition). Great intuition about such resonance with the field provides Couder’s experiments – see video and papers I’ve linked above.

Antenna , a problem

jarek, here as I wrote in my comment of March 7, 2012, the orbital angular momentum is an other varible to play with to increase the number of transmission channels for the same frequency without being bothered by the limitaions of the Shannon-Harley Theorem. However, here, the real problem will be to design a general-purpose antenna valid for the different L values. The team of this project seems to have some ideas about this problem.

Asghar, I think you meant this article: physicsworld.com…a-new-twist-on-radioIndeed extremely interesting. I thought about (micro-)orbit quantization of electrons, but as I understood, it is instead quantization of quantum phase (water don't have) because of the proper choice of velocity of circulating electrons. Created optical vortex is something very different from optical photons - like behind marine propeller - I think it could literally make something macroscopic rotate(?).'However, I think the belief in infinite informational capacity is greatly overestimated - like nonzero noise reduce capacity of continuous function to finite one by Shannon-Harley theorem. Using angular momentum would only add some degrees of freedom to it.ps. I apology for misspelling your name.

Update: Ragtime, thanks for the video - ok, I have to think about it. The rotation was not made by absorption, but some complex indirect interaction - could we rotate macroscopic object by just absorbing optical photons?

Ragtime, ok I has focused on 180deg rotation of electron's spin alone (what doesn't carry total angular momentum), but forgot that there is also change of orbital angular momentum of electron - this difference has to be carried by the optical photon. Richard Beth in 1936 has measured the tiny reaction torque due to the change in polarization of light on passage through a quartz wave plate: prola.aps.org…p115_1

Asghar, so what do you think of such Couder's classical quantum experiments?About angular momentum antennas, the possible gain is phase around the circle - with nonzero noise, there is finite information capacity there.ps. Please remove unnecessary quotes - they are really annoying.

ratio of am/lm from theory

Jarek, In the present experiment with the acoustic waves, the team found that ratio of the angular momentum the the linear momentum = intertwined helices per wavelength as predicted by the theory. This theoretical prediction can be obtained via the de Broglie relation λ = 2π h bar/mv: hbar/mv = anagular momentum as h or hbar is unit of am / mv = λ/2π. Simple!As to Couder's experiments,I shall try to look at them and then say something.

Ragtime, ok I has focused on 180deg rotation of electron's spin alone (what doesn't carry total angular momentum), but forgot that there is also change of orbital angular momentum of electron - this difference has to be carried by the optical photon. Richard Beth in 1936 has measured the tiny reaction torque due to the change in polarization of light on passage through a quartz wave plate: prola.aps.org…p115_1

Asghar, so what do you think of such Couder's classical quantum experiments?About angular momentum antennas, the possible gain is phase around the circle - with nonzero noise, there is finite information capacity there.ps. Please remove unnecessary quotes - they are really annoying.

3D soliton?

Thanks Jarek for explaining your views. Until more precise theories and experiments are created and performed , we can only guess at the exact shape of the photon (let us remember Einstein's caution late in his life about that!). Is there evidence or theory that the photon is an extended soliton and not just an infinitely spreading wave? Of course a soliton view is closer top the point photon idea upon which quantum mechanics was built? But what if the alternative view (not a particle or soliton) is correct? If so I think at any given moment the released energy of the photon will have a shape - not a spherical wavefront but a group wave as emitted from a dipole. Eric Reiter seems to have gone deeply into the theory behind his gamma ray beamsplitter experiments. I do not know of any outside confirmation but if it. Couder's hydrodynamic soliton is a surface phenomena I wonder how it will look like in a 'spherical liquid' simulation the more to simulate particles ?

Dr. Asghar by raising an alternate possibility for the deeper reason why the photon and particle behave the way they do I am not doubting the ability of the mainstream explanations that you give (and at which you are of course an expert) to describe reality. As you know not only dreamers like me but many academically qualified physicists find something deeply unsatisfying in the foundations of physics and wish to know why things behave the way they do, not merely how. Mathematics allows different explanations of the same phenomena, but until a model close to nature is discovered and proven to be true, no real progress in physics can be made using the clunky and sometimes mutually contradictory theories in use today.

By the way you made an amusing pun relating to Jarek's misprint of your name - permit me to make another and with respect- translating your name from Arabic to mathematese you get 1000< (M taken as a Roman numeral!)

Until more precise theories and experiments are created and performed , we can only guess at the exact shape of the photon (let us remember Einstein's caution late in his life about that!). Is there evidence or theory that the photon is an extended soliton and not just an infinitely spreading wave?

Vladmir, the problem is that practically nobody cares or searches for "shape of photon". They are satisfied with perturbative picture, forgetting that it's only an (divergent) approximation. It allows to work on particles by using effective coefficients describing their interactions - is perfect for calculations, but says nothing about what field configuration is behind obtained Feynman graphs ... or even photon.

So what do we know about optical photons? First of all they are undividable - usually given optical photon was produced by a concrete atom and will be absorbed by concrete another one ... undeformed even after years of travel.So it is stable, localized in area of length about the wavelength (2pi) - technically such field configurations are called solitons.What more? They carry energy, momentum and angular momentum - can physically heat up, push and rotate (even macroscopic object) - these are effects of conservation laws while atomic deexcitation - because of Noether theorem for correspondingly time, translation and rotation invariance.What more properties do they have? Something with weak/strong/gravitational interaction? No, only EM.So maybe any electric/magnetic moments? Not reallyThe only they have is energy, momentum and angular momentum - so basically they are twist-like wave - which (in opposite to waves behind marine propeller) doesn't dissipate (is soliton), because there is no viscosity in EM field.Not true?Quote:

Of course a soliton view is closer top the point photon idea upon which quantum mechanics was built? But what if the alternative view (not a particle or soliton) is correct?

Soliton is not a point - it has always nonzero radius and finite energy density (approximately Gauss distribution).What kind of alternative for optical photon you are thinking of? Not EM? Not undividable? Not carrying something?Quote:

If so I think at any given moment the released energy of the photon will have a shape - not a spherical wavefront but a group wave as emitted from a dipole.

Remember they have also angular momentum (as directly seen in movie linked by Ragtime) - this dipole had to rotate ... so created twist-like wave.Quote:

Eric Reiter seems to have gone deeply into the theory behind his gamma ray beamsplitter experiments. I do not know of any outside confirmation but if it. Couder's hydrodynamic soliton is a surface phenomena I wonder how it will look like in a 'spherical liquid' simulation the more to simulate particles ?

Let us leave gamma rays for now - they are undoubtedly much more complex.Couder's experiments cannot be directly translated to microscopic physics - they only give intuition about wave-particle duality and "quantum" phenomenas it results in.

Probability probably not fundamental

Thank you Dr. Asghar of course to misquote Newton from memory we are just like children on the sea-shore finding a prettier shell while the sea of knowledge stretches unknown before us. In a recent essay contest about whether reality is digital or analog I answered it is analog so I agree with your idea of basic granularity. However I totally disagree with Born's idea that probability is a fundamental aspect of reality. I have shown in my 2003 paper United Dipole Field and also in this figure from the 2005 Beautiful Universe paper that a normal distribution can emerge as a natural consequence of a causal, local, classical diffusion of e/m energy through an ordered universal lattice. I will write to you, The above papers and my email are also on my website . Despite my name I am an Arab :) سلام = salam = peaceQuote:

Vladimir, I do appreciate your thoughfulness. I have a weakness in insisting that our knowldge of the truth about things is only relative and it has to be and can be improved upon. As to dreaming (throwing oneself out of the daily caracan) is fundamental in all the creative adventure.( Allow me a small diversion: if possible, please send me your e-address, I shall send to you something about it. Here is mine: masgharfr@yahoo.fr. I do not think that we break any PW rules,here.)Physics that represent nature, in its ultimte finesse, has to be granular. We pass slowly from the CM with its continuos and completely predictable parameters to the granularity of QM controlled by probability, helped by the concerto of particle-wave duality. It bothers me to hear about the spoofyness of QM!If I am not wrong, you seem to know the Arabic language. Here, the word Asghar means "the small one" or something like piccolino, may be much smaller than a cherry petal!

Note: Vladimir, for some reason, I could not add directly to your text of comment.

My crazy ideas

Vladmir, the problem is that practically nobody cares or searches for "shape of photon". They are satisfied with perturbative picture, forgetting that it's only an (divergent) approximation. It allows to work on particles by using effective coefficients describing their interactions - is perfect for calculations, but says nothing about what field configuration is behind obtained Feynman graphs ... or even photon.

So what do we know about optical photons? First of all they are undividable - usually given optical photon was produced by a concrete atom and will be absorbed by concrete another one ... undeformed even after years of travel....Something with weak/strong/gravitational interaction? No, only EM.So maybe any electric/magnetic moments? Not reallyThe only they have is energy, momentum and angular momentum - so basically they are twist-like wave - which (in opposite to waves behind marine propeller) doesn't dissipate (is soliton), because there is no viscosity in EM field.Not true?...Soliton is not a point - it has always nonzero radius and finite energy density (approximately Gauss distribution).What kind of alternative for optical photon you are thinking of? Not EM? Not undividable? Not carrying something?

Jarek you are convinced of the photon picture as a soliton of limited size that is emitted whole by an atom and absorved whole by another. In my mind after emission the photon spreads (diffracts) as a wave and its energy quickly dissipates. This is the source of the uncertainty relations. In absorption the part of this wave reaching the atom is too weak to create an effect, but energy from many other photons is absorbed slowly until a threshhold quantum of energy is reached. It is the old so-called semi-classical theory that Eric Reiter is trying to prove experimentally. Naturally if this is so the shape of the photon in space at any one time is defined by its first and last wave-fronts. Think of a ripple tank where the vibrator stops after a while and the wave continues to propagate and expand. In my theory both gravity, e/m and everything else are different aspects of the same inductive interactions between ether lattice nodes. Sorry to keep repeating my crazy lattice idea but it seems to answer a lot of puzzles in different branches of physics.

Quote:

Remember they have also angular momentum (as directly seen in movie linked by Ragtime) - this dipole had to rotate ... so created twist-like wave.

In my idea of a propagating photon the angular momentum can occur because of two phenomena - the rotation of the energy pattern of the wave as a whole (helix-like) and also the rotation of the individual ether lattice nodes through which the wave pattern occurs.

Quote:

Couder's experiments cannot be directly translated to microscopic physics - they only give intuition about wave-particle duality and "quantum" phenomenas it results in.

Yes that was my impression that it was an inspiring phenomena but not an exact model of anything but itself.

Thank you Ragtime I am not dismissing hydrodynamic analogies - in fact I used them in my dediffraction research but point out they are limited to being an analogy because they do not have enough finess to describe all of the quantum world. Your first few links to images do not work. To answer your charge that I am 'locked' on my own ideas - a reasonable remark that was deleted together with my response!? : I am 'locked' into my research - having presented a ToE the culmination of 30 years of challenging study outside academia, which seems to me to answer many puzzles in physics- one of them the paradoxes of the double-slit experiment. It is yet to be proved or disproved, so I would be very grateful if it is critically read by those with more specialized expertise. Quote:

right hand rules

The linearity and chirality present in written scripts while adding letter to letter in loops and strokes is very interesting. In nature too there is linearity in superposition phenomena, and chirality in particle spin. The origin of the right-hand rule in electricity and magnetism must be part of the fundamental structure of space and matter. As to param it seems one of its meanings is 'the ultimate' I wonder how much our dreams to reach the ultimate truth about physical nature will be realized? Quote:

... a right to left script originated from 'Avestan', a right to left script of Sanskrit by Pharisee... Now, getting back to the interesting discussion which I like it- very enlightening. Unfortunately, it is Einstein's doing in science- make us go in circles- like the Pharisee some >10,000 years ago with right to left script... The concept of 'photon' is not real because photon does not exist. It is the "param..." that exists in reality and from which you, I or the tree including the Universe we live in are made...

Handedness

Vladimir, you are right that chirality or handedness in nature is a fascinating thing:1. Only the weak interaction creates handedness (violation of parity), say, for the spin of neutrinos and CP violation.2. In the matrix of life, only the left-handed aminoacids are active. Is this a genetic effect or due to the properties of orth and para-water molecules? There are some indications in both of these directions.3. Some languages are written from left to write and some from left to write, and some can be written from right to left and left to right and from up to down. Why? It could be due to some early cultural influences or the the nature of the characters of a language.4. The handedness in EM phenomenon, comes from the nature of these fields: the electic field in nonrotational and the magnetic field is rotational.

The linearity and chirality present in written scripts while adding letter to letter in loops and strokes is very interesting. In nature too there is linearity in superposition phenomena, and chirality in particle spin. The origin of the right-hand rule in electricity and magnetism must be part of the fundamental structure of space and matter. As to param it seems one of its meanings is 'the ultimate' I wonder how much our dreams to reach the ultimate truth about physical nature will be realized? Quote:

... a right to left script originated from 'Avestan', a right to left script of Sanskrit by Pharisee... Now, getting back to the interesting discussion which I like it- very enlightening. Unfortunately, it is Einstein's doing in science- make us go in circles- like the Pharisee some >10,000 years ago with right to left script... The concept of 'photon' is not real because photon does not exist. It is the "param..." that exists in reality and from which you, I or the tree including the Universe we live in are made...

It is wonderful that the Dundee team has experimentally verified the theoretical predictions. The question remains is: exactly how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum?

Water swirling asymmetrically out of a bath has both linear and angular momentum. In the same way, you should be able to make an asymmetric acoustic wave with similar properties. But if that's all it is, why the great fuss? do I hear someone utter the keywords 'grant application', 'hype'?

Water swirling asymmetrically out of a bath has both linear and angular momentum. In the same way, you should be able to make an asymmetric acoustic wave with similar properties...[quote=Vladimir Tamari;17409...The question remains is: exactly how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum?

In another recent thread (particle interference) I posted about another dunkedinbathexperiment concerning particle interference when the particle is larger than the double slits width:I have now posted an illustrated outline of the proposed experiment as "valavel" inphysics forumsQuote:

Dr. Asghar thank you ... Indeed new physics should come out of a theory closer to how nature actually operates: An experiment that occurred to me yesterday- in the bath like Archemides haha - is to repeat the particle double-slit experiment with slits that are smaller than the particle size. If interference occurs in spite of that, it will prove my idea that it is the gravitational field surrounding the particle that passes through both slits and interferes- not the particles themselves.Quote:

Key issue?

It is wonderful that the Dundee team has experimentally verified the theoretical predictions. The question remains is: exactly how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum?

Water swirling asymmetrically out of a bath has both linear and angular momentum. In the same way, you should be able to make an asymmetric acoustic wave with similar properties. But if that's all it is, why the great fuss? do I hear someone utter the keywords 'grant application', 'hype'?

Yes Sir, I agree the Key issue is "... how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum?" Or what makes "Water swirling asymmetrically out of a bath has both linear and angular momentum." ? A simple answer can be "force"- if so- who creates that force and how? Sorry, no short answer... wait to read the Book...

Things are simple

Brian, as you say, the things are rather simple: a particle or a wave of any kind that has linear momentum can be twisted to have aiso angular momentum and it happens all the time in nature: electrons in their atomic orbits, a merry-go-round...If one asks: what is the theoretical ratio of angular momentum to the linear momemtum? Here the de Broglie relation gives the answer: h bar/mv = λ/2π!

It is wonderful that the Dundee team has experimentally verified the theoretical predictions. The question remains is: exactly how and why on the sub-sub-atomic scale can a wave have this property of both angular and forward momentum?

Water swirling asymmetrically out of a bath has both linear and angular momentum. In the same way, you should be able to make an asymmetric acoustic wave with similar properties. But if that's all it is, why the great fuss? do I hear someone utter the keywords 'grant application', 'hype'?